1. Field of the Invention
The present invention relates to an imaging device and an imaging system.
2. Description of the Related Art
An image sensor, or an imaging device, includes a plurality of pixels including photoelectric conversion elements that receive light and convert the light into charges in accordance with the intensity of the received light. The pixels receive light directly entering the pixels and light leaking from adjacent pixels. Thus, the pixels are affected by such light leakage from the adjacent pixels. The light leakage has a more significant influence on smaller pixels. Thus, image sensors with far smaller pixels that are available these days cannot ignore the influence of the light leakage.
Japanese Unexamined Patent Application Publication No. 2011-066801 discloses an imaging system that can measure the quantity of light leakage between pixels in an image sensor. The image sensor disclosed in Japanese Unexamined Patent Application Publication No. 2011-066801 has a shaded pixel region. The shaded pixel region includes shaded pixels that are covered with metal and are optically shielded and open pixels that are not optically shielded and interspersed in the shaded pixels. In the imaging system disclosed in Japanese Unexamined Patent Application Publication No. 2011-066801, light leaking from an open pixel to a shaded pixel is measured as light leakage. By using the measured light leakage, the imaging system corrects light leakage (color mixing) from a pixel in a region that images a subject to a pixel of interest adjacent to the pixel.
When such an open pixel is formed by forming an aperture in the shading metal that covers the pixels, light entering from the aperture to the open pixel behaves differently from light that enters a region for imaging a subject due to some reasons such as differences in disposition of the metal. Thus, the imaging system described above has a problem in that the measured light leakage differs from the light leakage that actually occurs.